Solvent fractionation of vegetable oils is not widely practiced domestically. This procedure involves diluting a refined vegetable oil with several volumes of any suitable solvent such as a low molecular weight aliphatic ketone, e.g., actone or methyl ethyl ketone, containing 3 or 4 carbon atoms up to 20 volumes and chilling the solution to a predetermined temperature, separating the resulting crystals from the mother liquor, washing, etc. The greater the extent of dilution with the solvent, the sharper the fraction. 2-Nitro-propane may also be used as a solvent in the same way. This process may be repeated at a different, usually lower temperature, to derive various fractions having particular utility, e.g., low fat spread confection coatings, etc. The final mother liquor derived from the oil by whatever fractionation procedure is used, is commonly designated an "olein" fraction. The first crystal fraction derived from the oil is higher melting and is commonly called a "stearine" fraction. The solvent fractionation procedure allows much sharper cuts of the oil than solventless "graining" and filtering wherein the filter cake retains a substantial percentage of the base oil.
In the case of palm kernel oil, an imported lauric oil, the "C", or olein fraction, or base stock derived by solvent fractionation is largely a lauric/myristic (C.sub.12 -C.sub.14 ) normally liquid triglyceride. It is virtually unsaleable. In the cases of partially hydrogenated cottonseed, soybean or mixtures of these domestic oils, the stearine solvent fraction or hard stock (C.sub.16 -C.sub.18) is also of limited commercial utility. Both fractions pose, therefore, a disposal problem whether used as fuel or otherwise disposed of. It has now been found that a useful normally solid triglyceride material or hard butter having desired properties such as described below can be produced from these commercially unattractive triglyceride by-products by blending them and catalytically rearranging or randomizing the blend.
Before proceeding to a more detailed description of my process and product, it is helpful to recognize the qualities and physical properties which characterize the broad class of materials known as "hard butter". One should appreciate at the outset that heretofore there have been few recognized or accepted specifications on the chemical constitution of "hard butters". Materials which have been bought and sold in the "hard butter" markets for many decades have been bought and sold primarily on the basis of physical properties, physical performance, odor, taste and other edible qualities. So long as a material met such qualifications, neither the buyer nor the seller needed to give much consideration to the chemical constitution of the material other than to be satisfied that it was a food product composed mainly of triglycerides. The principal physical properties considered in a "hard butter" are its softening point, melting point, fracture quality and freedom from sweating. Good "hard butters" should have a Wiley melting point between about 76.degree. F. and 120.degree. F., preferably 84.degree. to 105.degree. F. and should be hard and brittle at around normal room temperatures; that is, they should break sharply and suddenly at about 75.degree. F., thereby having a brittle quality sometimes referred to as "snap". They should also be capable of standing at temperatures encountered in normal summer conditions without having liquid components thereof "sweat" or bleed out to the surface in the form of droplets or a visible liquid film. The Solid Fat Index at 100.degree. F. should be less than 20, preferably less than about 7.
The physical performance qualities of "hard butter" are numerous. One desirable quality is freedom from a "waxy" feeing or taste in the mouth; waxiness by this test is related somewhat to a narrow or sharp melting range although not entirely determined thereby. The other performance qualities are gauged largely by the performance of standard chocolate coatings, of which one typical formula is: 33% hard butter, 20% cococa and 47% sugar, with usually 0.2% lecithin. Such a coating, when prepared from the "hard butter" being tested, should set or harden in a few minutes under the normal conditions encountered in the commercial practice of enrobing or otherwise applying the coating to a candy center or food product which is to be coated or iced. Thus, in enrobing a center with the coating, the coating should set in the few minutes which are allowed for the enrobed center to pass through a cooling tunnel maintained usually at temperatures of 50.degree. F. or 60.degree. F. When the piece emerges from the tunnel, the coating should be firm enough to permit it to be packaged directly. The liquid coating which is used for such purposes should also have a viscosity at about 110.degree.-130.degree. F. or at temperatures near the melting point of the fat suitable for making smooth, uniform coatings, and should have a moderately short drip time after being applied as a coating on a food product such as a candy center. Another important performance quality is that of "stand-up". After a food product has been coated or iced, the coating and the "hard butter" therein should resist any appreciable changes in character when exposed at normal summer temperatures or at the temperatures which are apt to be encountered in the transportation of the coated products. This test for the coating is somewhat analogous to the "sweat" test for the hard butter itself, but a different characteristic is watched for in the "stand-up" test. For the purposes of this test, the coating should not soften so much as to stick to stain or discolor the material in which the coated product is wrapped, and should not run from high points on the coated product to lower adjoining regions. Two other properties of coatings of the type represented by the foregoing typical formula which are tested to determine the quality of the "hard butter" in the coating are the hardness of the coating are measured by a penetration test at room temperature, and the gloss of the coating. A high gloss on the surface of the coating is desired, and it is further desired that the gloss be retained when the coating is allowed to stand at room temperature. Some hard butters are known to give a high initial gloss, but in the course of a day or two the coating becomes dull. Another way important performance quality or hard butter skin to "stand-up" is its ability to prevent, minimize or fail to induce "greying" and "bloom" when coatings containing cocoa are aged. Coatings which have turned grey, due frequently to the coated product having been heated and cooled alternately a number of times, are very unsightly and unappetizing, and customers generally refuse to buy the confection or return it to the seller on the misconception that it has become spoiled. A candy manufacturer is naturally very much opposed to the use of a "hard butter" which induces or will not prevent the "greying" of such coatings.
Miscellaneous qualifications of "hard butter" are freedom from odor, obtained by the conventional deodorizing treatments applied to fats and oils, and a bland taste, obtained by refining the "hard butter" to eliminate free fatty acids, soaps and other impurities almost completely. Free fatty acids may be tolerated in amounts of up to about 0.05%.
Such then are the qualities and properties which the "hard butter" trade expects of the materials which are offered as "hard butter". Nevertheless, the trade recognizes various grades of "hard butter", suitable for different end uses. While the different grades are not governed solely by Wiley melting points, yet for the present purposes of explaining my invention, I may classify them roughly into the following five groups having Wiley melting points around the following values:
______________________________________ Wiley Melting GRADE Point, .degree.F. ______________________________________ 1 84 2 95 3 105 4 113 5 120 ______________________________________
Hereafter and in the claims where the term "hard butter" is used without further qualification, it will be intended to designate a material corresponding to one of the grades listed above and otherwise meeting present trade requirements in respect to the properties and qualities described above.